Orientated construction of visible-light-assisted peroxymonosulfate activation system for antibiotic removal: Significant enhancing effect of Cl-

Antibiotic contaminants can migrate over long distances in the water, thus possibly causing severe detriment to the environment and even potential harm to human health. Heterogeneous activation of peroxymonosulfate (PMS) assisted by visible light is an emerging and promising technology for the purification of such wastewater. This study designed an ultra-efficient and stable PMS activator (FeCN) to restore the typical antibiotic-polluted water under harsh conditions. About 90.94% of sulfamethoxazole (SMX) was degraded in 35 min in the constructed FeCN+PMS/vis system, and the reaction rate constant was nearly 50-fold higher than direct photocatalysis. Electron spin resonance, quenching experiments, LC/MS technique, eco-toxicity assessment, and density functional theory validated that the SMX removal was dominated by the attack of h+, •O2- and 1O2 on the active atoms of SMX molecules with high Fukui index, presenting as a simultaneous degradation and detoxification process. Such a visible-light-assisted PMS activation system also had good resistance to the environmental water bodies and a broad spectrum in the degradation of various pollutants. In particular, Cl- (50 mM) could significantly accelerate the removal of SMX with a 32.6-fold increase in catalytic activity, and the mineralization efficiency could reach 56.6% under identical conditions. Moreover, this Cl- containing system excluded the degradation products of disinfection by-products, and such a system was also versatile for different contaminants. This work demonstrates the feasibility of the FeCN+PMS/vis system for the remediation of antibiotic-contaminated wastewater in the presence and absence of Cl-, and also highlights their great potential in WWTPs.